The proposed research plan deals with several aspects of the chemical and functional asymmetry that exists in bacterial systems undergoing differential transcription of the genome, genetic recombination and DNA replication. Studies will be carried out during synchronous growth of bacteria and during morphogenesis (germination and sporulation of B. subtilis. We plan to continue our work using MAK fractionated DNA strands designated as light (L) and heavy (H). First, we plan to continue our investigations on the chemical asymmetry of DNA by determining the distribution of pyrimidine clusters (isostichs) in small segments of the genome and the purine catalogs after RNase A digestion of their transcription products. Second, we plan to establish the transcription pattern with respect to strand-switching and the synthesis of anti-sense messengers during spore germination, synchronous vegetative growth and spore formation. This will be done by hybridizations and hybridization-competitions using the separated strands and pulse-labeled RNAs made in wild-type populations, asporogenous mutants and during chloramphicol treatments. Third, the role of DNA asymmetry in recombination will be explored by following the fate of individually labeled L and H strands in heteroduplex molecules during transformation. Finally, the question of asymmetric bidirectional replication of the B. subtilis chromosome will be investigated by sequential mutagenesis with nitrosoguanidine. These investigations will further our understanding of the biological role of the chemical asymmetry in DNA in relation to chromosome duplication, transcription, genetic recombination and other events of recognition of control during bacterial differentiation.